In certain mass and/or rapid transit systems, such as, in subway and light rail commuter operations, the passenger cars are equipped with automatic couplers which are not only mechanically interconnected to the cars of the train but also are electrically and pneumatically coupled to the electric and air train lines ordinarily carried by the coupler housing. In a previous type of car coupler, the electrical portion normally included a plurality of electrical contact elements for interconnecting the train line circuits. The electric portion of a former coupler includes a slide frame assembly having a front slide frame and a rear slide frame. The front slide frame normally includes a metal collar or cover encasing the front insulating block which contains a plurality of spring-biased electrical contacts. The electrical contacts are pre-loaded by being abutted by an adjustable double-hex nut arrangement. The rear slide frame also includes a metal housing or cover which contains a rear contact block and a cured epoxy resin compound encapsulating the plurality of contact-associated terminal elements and the interconnecting insulated jumper wires. The train line circuit leads are solder connected to openings formed in the free ends of the terminals.
It will be appreciated that the prior art arrangement has a number of shortcomings and associated disadvantages. For example, it is virtually impossible to repair or replace a damaged jumper wire which is encapsulated in the mass of the cured epoxy compound. Accordingly, it is necessary to remove and replace the entire or complete rear slide frame when damage occurs to one or more of the jumper wires. Further, the construction of the prior art rear slide frame is relatively expensive since it involves a long drawn out multi-step manufacturing process or procedure. First, the metal cover must be initially partially machined from a crude casting. After placement of the terminal elements and situation and connection of the jumper wires, the epoxy resin is poured into the metal cover and is allowed to cure for an appropriate period of time. After a curing time of sixteen (16) hours at 176.degree. F., the final machining of the frame takes place. In addition, it has been found that the spring-biased electrical contacts are not removable from the exposed side of the front block, and that the whole front slide frame had to be removed before it is possible to replace the contacts. Further, it has been determined that during rainy weather and during car washing periods, water and cleaning solutions as well as dirt can seep through the clearance space between the contacts and the holes in the front block. This allows moisture to accumulate internally, which can cause corrosion of the contacts, the springs, and the double-hex nuts which can result in mechanical and electrical failure. Likewise, it has been found that the springs in the stationary electric contacts are susceptible to taking a permanent set when subject to high current surges.